MPEG DASH with H264 + H265

Question

I've tried to build an MPEG-DASH stream coding some bitrates in H264 and some others in H265. In a nutshell I'm trying to code the same video with ffmpeg for the lower bitrates in H264 and the highest ones in H265 (in order to get the benefit of the extra compression). In order to have both files aligned, I use the same GOP and keyframe sets for both enconders. The codification works fine but I get an error about the video aligment.

Anyone knows if wht I'm trying to do is supported in the stanndar and how to make it working?

Thanks